Actually, I was not expecting that. But nothing to be surprised about in my opinion because Arsenal in recent times has clearly shown that they have much more faith in their younger squad there than the experienced ones.
I think that's positive. Young people often work more in the field, because they want to show what they are capable of. They still don't have vices and usually don't think they're stars.
One thing that English football is good at is betting on young people with ease. If Arsenal are making that bet and having positive results, they have no reason to stop following that path.